Characterization Of Machining Defects In Wood Planing Operation
The objective of this study was to evaluate the effect of some machining factors on the machinability of selected Malaysian hardwoods and to quantify the major types of machining defects in the planing operation. The study aims to reveal the relationship between the types of surface defects gener...
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Format: | Thesis |
Language: | English English |
Published: |
2010
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Online Access: | http://psasir.upm.edu.my/id/eprint/12348/1/FH_2010_2A.pdf http://psasir.upm.edu.my/id/eprint/12348/ |
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Summary: | The objective of this study was to evaluate the effect of some machining factors on
the machinability of selected Malaysian hardwoods and to quantify the major types
of machining defects in the planing operation. The study aims to reveal the
relationship between the types of surface defects generated after planing with the
variable factors. It also studies the sanding process as an indicator to reveal loss
thickness (yield) after the planing process on defective planks.
For this research, three wood species, Rubberwood (Hevea brasiliensis), Melunak
(Pentace spp) and Dark Red Meranti (Shorea spp) were chosen based on their
machining characteristics, commercial position in the local and global market, and
their usage as a solid material in the furniture industry. 50 clear samples of each
wood species, for each treatment, in a uniform moisture content (10%), of the final
size of 19 by 102 × 910 mm, were machined by a planer unit, Weinig Unimat 23E
using only the bottom spindle of the machine. The cutterhead had 4 knives with a diameter 120 mm, rotating at 6000 revolutions per minute (RPM). The depth of cut
(0.8, 1.6 and 2.4 mm) and feed rate (8, 12 and 16 m/min) were the experimental
variables, while all other factors were kept constant. The surface quality of the
individual sample was examined both visually, and sense of tactile to classify the
samples into five grades based on the amount and severity of defects present, as
given in the standard (ASTM, D 1666 – 87).
In every instance, 60 percent or more of the samples were defect-free, and the
slightly defective pieces outnumber the more seriously defective ones, by a wide
margin. An in-depth analysis of the samples surfaces, machined under the three
parameters of processing, found that among these three factors, depth of cut had the
most significant effect on torn and fuzzy grain. This research also revealed that the
combination of feed rate, depth of cut and wood species used had no significant
effect on the surface quality of samples.
This research showed that the planing operation as a part of wood products
manufacturing can influence the quantity or volume of product parts manufactured
from a given amount of lumber and labor by affecting the processing yield. The
proper machining factors in relation to the wood species used decreases the surface
defects. These defects results in increasing labor cost, machining cost and loss of
wood material. Therefore, the optimal condition for planing operation of the three
Malaysian woods to produce the best yield was realized at the minimum of depth of
cut, and maximum cutting marks number per millimetre. |
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